Rob Duivis – KLM Bloghttps://blog.klm.com
Royal Dutch AirlinesSat, 25 May 2019 13:19:52 +0200en-UShourly1https://blog.klm.com/assets/uploads/2018/03/cropped-favicon-120x120.pngRob Duivis – KLM Bloghttps://blog.klm.com
3232Jet engine propulsion; the comparison of power between a car and an aircraft?https://blog.klm.com/jet-engine-propulsion-the-comparison-of-power-between-a-car-and-an-aircraft/
https://blog.klm.com/jet-engine-propulsion-the-comparison-of-power-between-a-car-and-an-aircraft/#commentsThu, 06 Dec 2018 16:03:39 +0000https://blog.klm.com/?p=81810As the reference for people is very often their automobile, people like to compare the power of an automobile engine with that of an aircraft engine. In this blog I will try to explain why this comparison does not make sense. How do we express the power or thrust (as it is in this case […]

]]>As the reference for people is very often their automobile, people like to compare the power of an automobile engine with that of an aircraft engine. In this blog I will try to explain why this comparison does not make sense. How do we express the power or thrust (as it is in this case called) of a gas turbine engine used for aircraft propulsion?

Piston engines in cars are fundamentally different from aircraft engines

In the automotive sector and in light aircraft, piston engines are used. These engines, different from large commercial aircraft engines, produce power generated at the crankshaft where the pistons are attached to.

With a piston engine used in a car, the crankshaft is connected to the drivetrain that moves the wheels. And with a piston engine used for aircraft propulsion, the crankshaft drives the propeller. It acts as the fan with a large turbofan engine. The power output of a piston engine is expressed in watts or in the old days in horsepower. 1 horsepower equals 746 watt.

How does a jet engine work in simple terms?

In a jet engine air is sucked in the inlet. After that it’s compressed in the compressor to high pressure and mixed with fuel in the combustor. The hot gases flow backward through the turbine system. This drives the compressor system and the air leaves the engine at the end through the exhaust system.

So how does the engine produce the power that moves the aircraft forward? This is where one of the greatest scientific geniuses comes aboard: Mr. Newton.

Newton was one of the most famous physicist that lived between 1643 and 1727. He formulated several laws of physics. Two important ones for the working fundamentals of a jet engine:

There is a direct relation between the movement of a body and the force applied to it

When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.

And this explains exactly the fundamentals of how a jet engine works.

A gas is accelerated through the engine in rearward direction. As a consequence, a force equal but in opposite forward direction is exercised by the engine. Because the engine is attached to an aircraft, the aircraft moves in that same direction!

The laws of physics in Newtons

So now we know that a jet engines produces a force that moves the aircraft through the air. The force that is generated by the jet engine is called thrust. In its simplest form it is a force applied to the aircraft in the direction of flight. This force is expressed according the laws of physics in Newtons. Depending on the different measuring units this is expressed in Newtons, Kilograms or pounds of force. 1 Newton equals 0.102 kilograms and that equals 0.225 pound of force.

This sounds like a huge amount of force, but modest compared to rocket engines. Just to give you an idea: The Space shuttle was launched with 7.3 million pounds of thrust!

So the comparison between a piston engine and a commercial aircraft jet engine is not easy. These are two entirely different engines! To compare the power of a commercial aircraft jet engine to an engine used in a car, you need to convert thrust to shaft power to compare this with the crankshaft of a piston engine.

How should we do this?

If we take aircraft weight, speed and drag (the resistance of the aircraft moving through the air) all into account, we can calculate a theoretical number of Watts produced by the engines. 1 Megawatt equals 1341 horsepower. For an aircraft like a Boeing 777 with two GE 90-115B engines each engine produces roughly 23 Megawatt of power during cruise flight with a fully loaded aircraft. This is 30.843 horsepower.

Another way to look at the comparison; the GP 7200 engine or the Airbus A380 equals at take-off for all four engines around 230 Megawatt of total fanpower. That is the power required to drive the fan of the engines. This equals 308.435 horsepower, so each engine produces about 77.109 horsepower to drive the fan during take-off! To give you an idea, a Formula 1 engine produces around 800 horsepower. This is excluding the additional hybrid electrical power. An average car produces 100 horsepower or 75 kilowatt.

Conclusion

All in all, comparing aircraft engines power output to the expression of poweroutput of a piston engine of a car is a bit more complicated. Why is that? Due to the differences in the physics of a car compared to an aircraft it’s just not that simple to compare the two ways of transportation. The power of an aircraft engine is expressed in newtons, kilograms or pounds of force. The piston engine delivers the power to a shaft that either drives a car or drives a propeller in light aircraft. This is measured in Watts, or horsepower in the old days.

]]>https://blog.klm.com/jet-engine-propulsion-the-comparison-of-power-between-a-car-and-an-aircraft/feed/3A second life for an old birdhttps://blog.klm.com/a-second-life-for-an-old-bird/
https://blog.klm.com/a-second-life-for-an-old-bird/#commentsFri, 26 Oct 2018 14:24:43 +0000https://blog.klm.com/?p=80942At Engine Services we have begun a relatively unique project. We are preparing an aircraft engine to be exhibited outside Building 404, KLM Engineering & Maintenance’s headquarters. There’s nothing better than tinkering with an aircraft engine. Sometime in mid 2016, VP Engine Services, Paul Chün, called me and my colleague Edu van de Haar to […]

]]>At Engine Services we have begun a relatively unique project. We are preparing an aircraft engine to be exhibited outside Building 404, KLM Engineering & Maintenance’s headquarters.

There’s nothing better than tinkering with an aircraft engine.

Sometime in mid 2016, VP Engine Services, Paul Chün, called me and my colleague Edu van de Haar to his office. “I have received a request from Ton Dortmans, VP KLM Engineering & Maintenance, to look into the possibility of having a static aircraft engine on display at Schiphol Oost. Do we have a written-off engine we could use?”

What began with a simple question ended with a plan for an opened-up aircraft engine on permanent display at Schiphol Oost near Building 404, the headquarters of KLM Engineering & Maintenance. We want to show our customers and anyone else who is interested, what we do and what our technical skills are.

The project will take more than a year and will be unveiled around KLM’s centenary anniversary. During the preparations, we will produce a series of blogs, with photographs and films, to record what we are doing and to show what is involved.

Plan

After detailed consultations with a number of departments at Engine Services, we eventually found a financially depreciated General Electric CF6-50 engine, which is the type that was fitted in the DC10s and older models of the Boeing 747 and Airbus A300.

The question was, how should we tackle it? What do we want to end up with, exactly? Where and how are we going to position the engine, what do we want to show, what needs to be done and who’s going to do it? Important questions, because nothing can be allowed to interfere with day-to-day business.

A plan emerged from the necessary brainstorming sessions: We would partially open up the engine to show the internal airflow. All the parts that obstruct the view of the inside of the engine are to be removed, carbon-neutral lighting is to be fitted, as are electric motors to rotate the engine.

The engine’s diameter is more than two metres, it weighs 4,000 kilos and is around six metres long. We want to place it on a concrete plinth so that you can easily see inside. The engine has to be able to stand up to the Dutch climate. And we will attach an air intake and outlet, which we will source from an aircraft disassembly company.

We now had a plan for what we were going to do. The question was, who was going to do it?

The idea was out forward to place the project in the charge of enthusiastic, experienced (retired) former KLM employees working with a team of students from the regional aviation college (ROC). In this way, KLM production staff can still get on with the day-to-day running of the business, while the students (perhaps KLM engineers in-the-making) get a wonderful opportunity to gain experience working on an aircraft engine.

We’re off!

We eventually started work in the summer of 2018 and have now stripped the engine of all unnecessary parts. The combustion chamber, and the high- and low-pressure turbines have been removed and partially dismantled, and part of the high-pressure compressor – the top case – has been removed.

The students were supervised by practical supervisors who taught them how to follow the correct instructions and how to use the manuals. The ultimate aim of their training is to find them a job in the aviation industry where everything revolves around compliance with regulations and using the correct documentation. This group has now returned to the classroom and a new group of students will begin later in the year.

In the next blog we will show you how far we have got to in the project.

]]>https://blog.klm.com/a-second-life-for-an-old-bird/feed/2The Reliable Jet Enginehttps://blog.klm.com/the-reliable-jet-engine/
https://blog.klm.com/the-reliable-jet-engine/#commentsFri, 02 Feb 2018 08:34:19 +0000https://blog.klm.com/?p=60578/In this series on aircraft and engine technology, I’ve regularly discussed innovations and development. Some people would love see things progressing even faster, but these things take time, especially in the air transport industry, with its high standards and strict regulations. In this blog, I’ll be taking a look at the development of jet engines […]

]]>In this series on aircraft and engine technology, I’ve regularly discussed innovations and development. Some people would love see things progressing even faster, but these things take time, especially in the air transport industry, with its high standards and strict regulations. In this blog, I’ll be taking a look at the development of jet engines and how they became so incredibly reliable.

The mid-1950s

Gas turbine or jet engines have been used in commercial aviation since the mid-1950s, when the first jet-powered airliners, including the British Comet and the American Boeing 707 and Douglas DC-8, took to the air.

The gas turbine engine has undergone an incredible evolution since those early days. From a straight jet, in which all the incoming air passed through the engine itself, to the current bypass engines, in which most of the incoming air flows around the central propulsor.

A lengthy process

This modern design has two major advantages: the engine produces much less noise and fuel consumption is much lower. Developments like this don’t happen overnight, mainly because the technology is complex and because of the strict safety and reliability requirements that apply for all aspects of aircraft engineering and operations.

How long does it take to develop a new engine?

Roughly speaking, a manufacturer will spend around 10 years developing and introducing a new engine. The initial design phase is, of course, guided by the aircraft type for which the engine is intended. Throughout the design process every component is carefully tested, which eventually leads to the first tests of the fully assembled engine in a special test cell.

During these ground tests, the engine is subjected to all sorts of extreme forces and operational scenarios. Later, the engine is also tested on specially designed test aircraft.

Once the engine has successfully completed airworthiness certification, it may be used for commercial aviation.

This process takes many years to complete and the main reason for this is safety. It is this lengthy and meticulous process that has brought commercial aviation to where it is today: a safe and reliable means of transport. The aviation industry continuously seeks ways to improve existing engine types. This process goes on throughout the working life of an engine, during day-to-day operations. It never stops.

What is the lifespan of an engine and aircraft type?

An aircraft can remain in commercial operation for up to 25 years. And engines may have an even longer lifespan, partly because of the preceding development and certification period. But also due to the fact that there are certain engine types which are used at different aircraft models, optimizing the economical usage.

And exactly how reliable are turbine engines nowadays?

In the early days of the Jet Age, engines had to be removed for a full overhaul after a relatively short span of time in operation. This operating time is usually expressed in flight hours. Back in those days, an engine was removed and overhauled after 2,000 flight hours.

Nowadays, operating time between major overhauls has been extended to around 20,000-25,000 flight hours. We fly wide-body jets equipped with just two engines to all corners of the globe. This evolution can be mainly attributed to the enormous gains in engine reliability over the decades.

So, when you next board a plane, maybe take a moment to remember that the industry spent 10 years ensuring that the aircraft and its engines are perfectly suited to your flight, and that the process of ensuring their reliability goes on constantly. It never stops.

]]>https://blog.klm.com/the-reliable-jet-engine/feed/13Meet Sir Frank Whittle: Father Of The Jet Enginehttps://blog.klm.com/sir-frank-whittle/
https://blog.klm.com/sir-frank-whittle/#commentsWed, 09 Aug 2017 15:09:32 +0000https://blog.klm.com/?p=53368/If you’re boarding a jet-propelled aircraft today, 9 August 2017, then this might be an ideal moment to pause and remember the man who stood at the cradle of turbine-propelled flight: Sir Frank Whittle. The inventor of the jet engine died twenty-one years ago on 9 August 1996. Born in Coventry, England on 1 June […]

]]>If you’re boarding a jet-propelled aircraft today, 9 August 2017, then this might be an ideal moment to pause and remember the man who stood at the cradle of turbine-propelled flight: Sir Frank Whittle.

The inventor of the jet engine died twenty-one years ago on 9 August 1996. Born in Coventry, England on 1 June 1907, Whittle’s career began as a trainee pilot in the Royal Air Force in the 1920s. Owing to his technical ingenuity, he was admitted to officer training in 1926, which called on him to write a thesis.

His thesis, Future Developments In Aircraft Design, included a design for a motorjet, a piston engine that channelled compressed air into a combustion chamber, which embroidered on an existing design. Whittle demonstrated how the engine could be useful for high-altitude flight.

Birth of the turbojet

Using a piston engine presented a problem, because it was heavy – always an important factor in aviation. Whittle ultimately came up with idea of a turbine that drives a compressor, which saw the birth of the first turbojet, the predecessor of modern gas-turbine engines.

To be honest, engineers in other countries were also working on turbine engines, because aircraft were becoming larger and heavier, which meant piston engines driving the propellers were becoming increasingly complex and less reliable.

Whittle with one of his first designs and in his office

A £5 patent

In 1930, Whittle patented his first design which the RAF considered unfeasible for aviation at the time. In the early 1930s, he completed his engineering training at the RAF, graduating with excellent marks that confirmed his technical ingenuity. In 1935, his patent for the turbine engine expired. Unfortunately, he didn’t have the £5 he needed to extend the patent at that time, which meant it became public. He then teamed up with a number of fellow students and colleagues to establish a partnership, which eventually developed into the company Powerjets, which continued to proceeded to further develop the turbojet.

The De Havilland Comet, the first jet-propelled passenger aircraft

The Whittle Unit

The pressure increased because German engineers had designed a working jet engine in the mid-1930s. The engine was intended for the propulsion of a Heinkel aircraft. The British Ministry of Aviation decided to get involved in the development of the “Whittle Unit”, as the first engine was called.

The first Whittle Unit was tested in April 1937 at the Bristol Thomson Houston Plant in Rugby. The first aircraft equipped with the engine was a Gloster Meteor, which took to the air in 1941. But competition was fierce, because the Italians had already completed their first jet-propelled flight with a CC2 in 1940, while the jet-propelled Heinkel had already completed its first flight the previous year.

The Douglas DC-8

The advent of the jet engine

Development of the jet engine was fraught with problems. Progress only came up to speed after the Second World War. Work on Whittle’s design signalled a decisive change. Whittle’s initial design weighed about a thousand kilos and generated about 631 kg of thrust. Compare that to the Boeing 787’s General Electric Genx 1B engine which weighs more than 6,100 kilos and has 34,000 kg of thrust.

The first commercial aircraft to use jet engines appeared in the 1950s. They included the De Havilland Comet, the Boeing 707, and the Douglas DC-8.

The B787 GEnx engine

A shining example

These days, jet engines exist in a variety of designs. Most large-scale passenger aircraft use turbofan engines. Smaller regional aircraft such as the Fokker 50 might use turboprops.

We remember Sir Frank Whittle as an ingenious designer with enormous passion and dedication, who played a major role in the development of the jet engine and in aviation as a whole. Thank you, Sir.

]]>https://blog.klm.com/sir-frank-whittle/feed/20The Progress of Solar-Powered Flightshttps://blog.klm.com/all-aboard-the-solar-impulse/
https://blog.klm.com/all-aboard-the-solar-impulse/#commentsWed, 26 Apr 2017 11:43:19 +0000https://blog.klm.com/?p=48244/Nowadays, we are seeing more and more cars with some form of electromotor. Some are fully electric, while others are hybrids that are partly powered by electricity and partly by fossil fuels. The big question is: will we ever see passenger planes powered by electricity? Nowadays Today’s aircraft are, of course, still powered by fossil […]

]]>Nowadays, we are seeing more and more cars with some form of electromotor. Some are fully electric, while others are hybrids that are partly powered by electricity and partly by fossil fuels. The big question is: will we ever see passenger planes powered by electricity?

Nowadays

Today’s aircraft are, of course, still powered by fossil fuels. These fuels are not infinitely available and they have another disadvantage: CO2 emissions. It goes without saying that we need to find viable alternatives. Together with various partners, KLM is spearheading the airline industry’s quest for alternative power sources, such as biofuels.

Major Challenges

The power source for propulsion will change in the long term. Electrically powered engines sound very promising, but there are major technological challenges to be overcome. One problem being the required engine power. More specifically: we do not yet have an electromotor that can match the power of a gas-turbine engine.

And then there’s the issue of power storage. A litre of kerosene contains a lot more potential energy than that which can currently be stored in batteries. However, efforts are underway to come up with a brilliant solution. I’m particularly impressed with the Solar Impulse project headed by the Swiss team of Bertrand Picard and André Borschberg.

Solar-powered flight

The Solar Impulse is propelled by electric propeller engines that are fed by solar panels. The aircraft completed a flight around the world in 2016; a 40,000-kilometre journey, with several landings along the way. The aim of the flight was to promote reusable energy, which is part of a growing energy awareness that is gradually spreading worldwide. Moreover, the flight confirmed that solar-powered air transport is (in principle) possible.

Would you board an electric KLM plane?

Personally, I would be at the front of the queue. As I said, there are still huge technical challenges to be overcome. It’s also hard to say if electrical propulsion is a viable option for large passenger planes. One thing is certain: a lot of research is being done in this field. It’s an important trend in the aviation industry, with a wide array of alternative fuels being researched:

Hydrogen;

Liquid natural gas;

Biofuels;

Hybrid forms of the above.

The latter envisages a combination of a very powerful gas-turbine engine, supplying the required power for take off, in combination with a second engine, which might be electrically powered, for example. The latter would be used at cruising altitude, where less power is required.

Biofuels and the fleet of the future

At KLM, we are working hard to modernise our fleet. One example is the B787 Dreamliner, whose engines burn 20% less fuel and emits 20% less CO2 than its predecessors. We are also making good progress with the use of biofuels. This is quite a challenge, of course, but we are gradually giving shape to the logistical chain required to used biofuels worldwide.

If we really want this new technology, why is it taking so long to develop?

The answer is simple: no other transport sector can match our efforts to develop innovative technology. Commercial aviation is unique in this regard. Once an idea is considered suitable for development, the real work begins. What follows is a lengthy process of certification and fine-tuning of technology and systems until the design is declared airworthy. This is an important process, because it ensures the high standard of safety that our industry has achieved over the years.

The short run

In the coming years, I foresee that engine manufacturers will make their existing designs even more efficient and silent. They will do so by applying new materials and by further perfecting gas turbines. We may also see the hybrid forms of propulsion I mentioned earlier appearing on the market.

One thing is certain: we will continue to keep you posted on all these developments!

If you’d like to read more about the future of aviation, clickherefor a blog about AHEAD, a project researching alternative aircraft designs.

And if you’d like to learn more about the Solar Impulse, please visit solarimpulse.com.

]]>https://blog.klm.com/all-aboard-the-solar-impulse/feed/1Is This The Future Of Aviation?https://blog.klm.com/is-this-the-future-of-aviation/
https://blog.klm.com/is-this-the-future-of-aviation/#commentsWed, 15 Mar 2017 09:00:31 +0000https://blog.klm.com/?p=17411These days, aircraft consist largely of a cylindrical fuselage with wings attached. The design has been in use for decades. A new study—called AHEAD—shows that aircraft design can be different. Could this be the future of aviation? AHEAD stands for Advanced Hybrid Engine Aircraft Development. AHEAD is a long-term aircraft design study led by the […]

]]>These days, aircraft consist largely of a cylindrical fuselage with wings attached. The design has been in use for decades. A new study—called AHEAD—shows that aircraft design can be different. Could this be the future of aviation?

AHEAD stands for Advanced Hybrid Engine Aircraft Development. AHEAD is a long-term aircraft design study led by the Delft University of Technology in the Netherlands along with a variety of academic and manufacturing partners throughout the world. KLM Engineering & Maintenance participated in this study and helped design the AHEAD Aircraft that can carry 300 passengers over a range of 14,000 kilometres.

Why did we participate in this study?

In a high level design study like this, designers—in their enthusiasm to develop a high-tech aircraft—cannot always see every practical implication of their design. The drawing board is very different to real-life practice and operation.

That is why KLM Engineering & Maintenance (as one of the possible future users of these aircraft) was invited to participate in the various design teams and to add a critical eye to the practical usage and operation.

I enjoyed participating in these sessions. We had intense discussions with smart and inspiring people with different cultural backgrounds, but all passionate about aviation and technology.

Aircraft fuselage and wings in assembly

Why this design?

The AHEAD aircraft design has an integrated wing and body, called a blended wing body design.

Minimizing resistance (or drag) is one of the main challenges in aircraft design. Overcoming drag requires power, and this results in greater fuel consumption. A blended wing body is one of the very promising designs to minimize the drag and, is so doing, making aircraft much more fuel-efficient.

The propulsion systems—that is, the engines—according to engineers.

Jet Engine Development

The jet engines currently in use are called turbofan engines. This is how they work. Large volumes of air flow through and around the engine. Some of that air is used to burn kerosene fuel in a combustor. The heated air then drives the turbines that in turn drive the compressors and that make up the entire propulsion system.

AHEAD involves a totally new engine design—a hybrid engine using two different combustion systems. The first combustor burns either cryogenic hydrogen or liquefied Natural Gas (LNG), the second combustor burns either kerosene or biofuel. By using two different combustor and fuel systems the engine’s total efficiency increases and emissions are reduced.

Counter Rotating Fan

Another feature of the engine of the future is the use of a counter-rotating fan. The large fan that produces most of the engine thrust is made up of two rows of blades that rotate in opposite directions. The advantage of this design is improve engine efficiency even further.

See You in 2050

The AHEAD design is a long-term study, with many aspects yet to be researched. The timeframe for introduction of an aircraft of this type is expected to appear sometime around 2050. KLM is committed to staying involved in short- and long-term innovations in aviation. I will keep you posted about the efforts and developments!

Sounds familiar?

It’s quite possible you’ve heard or read this before. We’ve posted this blog in August 2015. So this actually is a repost. But let’s be honest: you can’t get tired of reading about our innovative developments, right?

]]>https://blog.klm.com/is-this-the-future-of-aviation/feed/43This is what cycling, flying and KLM have in commonhttps://blog.klm.com/this-is-what-cycling-flying-and-klm-have-in-common/
https://blog.klm.com/this-is-what-cycling-flying-and-klm-have-in-common/#commentsFri, 13 Jan 2017 09:04:43 +0000https://blog.klm.com/?p=43802/As a lover of cycling, flying and KLM, the moment was bound to arise when I would wonder if those things had anything in common. When I first thought about it, there was nothing else to do other than find the common denominator. And guess what. There’s a lot! The Wright brothers To start, the […]

]]>As a lover of cycling, flying and KLM, the moment was bound to arise when I would wonder if those things had anything in common. When I first thought about it, there was nothing else to do other than find the common denominator. And guess what. There’s a lot!

The Wright brothers

To start, the Wright brothers, builders of the first motorised aeroplane, were originally bicycle manufacturers. Before making their first flight, on 17 December 1903, they had gone through numerous designs. One design of other pioneers stood out. It had a propeller driven by a cyclist! Suffice it to say that particular design didn’t make it to the final round.

Conditions for design

A Boeing 747-400 taking its 400 tonnes into the air or a lightweight racing bike of barely eight kilos “flying” over the roads – the similarities might not seem obvious, but they’re there. In both the design of the Boeing 747-400 and the racing bike, weight, integral strength, and wind resistance are central issues. For both designs, light but strong materials are used such as aluminium, titanium, and carbon composites. In flight, it allows for greater fuel efficiency. In cycling, it lets you go as fast as possible using the minimum amount of energy.

Aerodynamics

Aerodyna-what? Aerodynamics – the study of the interaction between the air and solid bodies moving through it. This knowledge is used when designing aircraft and fast bicycles. In both cases, it’s important that wind resistance is minimal because resistance calls for energy, whether from aircraft engines or from the cyclist on the bike. That makes it necessary to study air flow to create the best possible aircraft or bike. Aerodynamic research takes place in wind tunnels. In the case of the aircraft, designers will use a scale model in the air flow. For racing bicycles, you need both the bike and the rider in the air flow.

The Netherlands

Another interesting point, but one that involves civil aviation and bicycles, is the number of bikes that KLM transports each year – for instance, the bikes that our passengers take when they travel. From New York to Paramaribo to the Himalayas, you’ll find Dutch people on their bikes. Whenever I’m abroad I too am interested in the cycling culture of the country I’m visiting. How do the roads look? Can I cycle here? Often to come to the conclusion that life is very good for cyclists in the Netherlands. We have bike paths, traffic signs, rules and regulations and excellent infrastructure.

Me, myself and I

I said it before – I’m a lover of cycling, flying and KLM. Bicycles and everything that has to do with them – whether technology or sport – are my passion. As is KLM. I thought about the why of it all and came to the conclusion that cycling is in the DNA of the Dutch. We grow up with cycling. And we grow up with KLM.

And me? I took it to the next level and wove both cycling and KLM into my adult life. I started working at KLM at the age of 18. I was living in Amsterdam at the time, the city known for – you guessed it – its thousands of bicycles. More than 800 thousand of them. And on one of those bikes, I cycled through any kind of Dutch weather to and from work. I still do it to this day. And with every turn of the pedals, my love for cycling, flying and KLM continues to grow.

]]>https://blog.klm.com/this-is-what-cycling-flying-and-klm-have-in-common/feed/110 Things You Didn’t Know About Biofuelhttps://blog.klm.com/10-things-you-always-wanted-to-know-about-biofuel/
https://blog.klm.com/10-things-you-always-wanted-to-know-about-biofuel/#commentsSun, 20 Nov 2016 19:05:29 +0000https://blog.klm.com/?p=41238I look back with a hint of melancholy on some periods during my 41-year career at KLM. The year 2009, for example. Back then I was working as a test engineer at Engineering and Maintenance (E&M). A team of colleagues from various departments was working enthusiastically and especially hard preparing for the very first KLM […]

]]>I look back with a hint of melancholy on some periods during my 41-year career at KLM. The year 2009, for example. Back then I was working as a test engineer at Engineering and Maintenance (E&M). A team of colleagues from various departments was working enthusiastically and especially hard preparing for the very first KLM flight powered by biofuel.

That first flight, operated using Boeing 747-400 equipment, was a demonstration flight above the Netherlands. In terms of preparation not an easy job given considerations related to technology, logistics and legislation and regulations. Before its take-off on 23 November 2009, this partially driven biofuel flight enjoyed broad-based support.

And although biofuel flights are now more or less commonplace and CSR is firmly rooted in KLM and other companies, I’m regularly asked questions about biofuel flights. So I’ve gathered up 10 of them, along with the answers, in this blog.

Engineering Project Team

What is biofuel produced from?

Biofuel is produced from renewable feedstock such as plant oils, agricultural waste and wood chips instead of fossil fuels.

How do biofuel and biodiversy go together?

KLM only uses sustainable feedstock for its biofuel. That doesn’t have a negative impact on biodiversity or local food security for that matter.

What are the CO2 benefits of biofuel?

CO2 benefits depend on the feedstock and logistics.
Camelina is a plant that grows on Mediterranean soil with little to no fertility and has no negative effects on the production of nearby crops. It can reduce CO2 to about 70% compared to fossil kerosene. And compared to used cooking oil to about 80%.

When was biofuel first used on a commercial flight?

Biofuel was certified for aviation in 2011 and KLM was the first airline to fly with biofuel on a commercial flight. The biofuel was supplied by SkyNRG, a Dutch company established by KLM and others, which is now the market leader in providing sustainable jet fuel.

Do other forms of transport use biofuel?

Biofuels for transport have been around as long as cars have. At the start of the 20th century, car manufacturer Henry Ford planned to fuel his Model Ts with ethanol, and early diesel engines were shown to run on peanut oil.

Is biofuel expensive?

The price of sustainable biofuel has dropped from six times the price of fossil kerosene to two to three times since 2012. To be able to develop a market and purchase this biofuel, KLM is supported financially by multinationals like Heineken, Accenture, ABN AMRO and Friesland Campina through the KLM Corporate BioFuel programme.

How is biofuel supplied?

Oslo Airport Gardermoen was the first airport to add biofuel to its existing fuelling system at the beginning of 2016. Until then, biofuel had to be supplied by separate tank trucks.

Are there flights that use 100% biofuel?

It’s not yet possible to operate flights using 100% biofuel. Due to aviation’s strict quality guidelines, biofuels are always mixed with conventional fossil kerosene to a maximum of 50%.

Do engines need adjustment when using biofuel?

Biofuel is a so-called “drop-in” fuel? This means you can simply add it to fossil kerosene and use it without any adjustments to the engines.

Does KLM use biofuel on all flights?

No, not yet all KLM flights world-wide. But KLM did start using biofuel on all flights from Los Angeles this year and will do so for the next three years. This fuel is supplied by SkyNRG from the new Los Angeles-based bio refinery AltAir Fuels.

]]>https://blog.klm.com/10-things-you-always-wanted-to-know-about-biofuel/feed/8How Do We Test Jet Engines?https://blog.klm.com/how-do-we-test-jet-engines/
https://blog.klm.com/how-do-we-test-jet-engines/#commentsMon, 07 Mar 2016 08:30:54 +0000https://blog.klm.com/?p=29100In previous blogs we have discussed the repair process of our aircraft engines and what it takes to get the engine into good shape. Now let’s talk about the test process for a jet engine. When do you test a jet engine? Jet engines are tested on a number of occasions: during engine design and […]

]]>In previous blogs we have discussed the repair process of our aircraft engines and what it takes to get the engine into good shape. Now let’s talk about the test process for a jet engine.

When do you test a jet engine?

Jet engines are tested on a number of occasions:

during engine design and the development process at the manufacturer;

during engine installation on the aircraft following maintenance on the wing;

following overhaul, repair or inspection in the engine shop.

Engine tests during the design and development process

The manufacturer conducts extensive tests at remote areas both outdoors and indoors in a test facility.

Outdoor development testing

The tests need to demonstrate that the engine can meet its design goals and withstand events such as:

ingestion of debris, dust, sand, etc.;

ingestion of hail, snow, ice, etc.;

ingestion of excessive amounts of water.

Development tests take several years throughout the entire engine development program and consume a significant part of the total development costs. All of this is necessary to prove the engine meets all the operational and safety requirements.

Indoor development testing of icing conditions

On-wing engine testing

Once the aircraft is certified and in operation with the airlines, engines are frequently inspected once the engines have been installed on the wing. At the conclusion of these inspections or after engine replacement, the engines are tested on the wing at various power levels.

Engine tests on-wing are conducted for various reasons and include tests such as:

power assurance check, to verify that the engine is capable of producing the required thrust;

vibration and balance checks to check and, if necessary, balance the engine rotors;

oil and fuel system checks;

leakage checks to verify that all systems are free of leakage.

The engine test on-wing are conducted in the open field or in the vicinity of the hangar.

On wing testing of KLM aircraft

Off-wing engine testing

When an engine is repaired, inspected or overhauled in the engine shop, it requires an extensive series of tests to ensure that the engine is fit for reinstallation again. These tests are much more extensive compared to the on-wing engine tests. After a disassembly and rebuild we want to be absolutely sure the engine meets all the technical requirements and is fit and safe to operate again.

An off-wing engine test is done every five years, more or less, after it reaches the maximum flying hours and is refurbished.

A GE CF6 Engine test in operation in the KLM test facility

Where do we test after overhaul?

Post-overhaul engine tests are conducted in a controlled environment called a test cell or test facility. A test cell is a closed facility that is extensively instrumented and calibrated and allows for engines tests regardless the environmental conditions. See the video at the end of this blog.

AIR FRANCE KLM has two modern test facilities in place – at Schiphol Airport and Charles de Gaulle airport – enabling testing of all the engines we maintain, from B737 CFMI CFM56-7B engines up to the B777 GE90 115B engines. In the near future it will include the B787 GEnx engines.

Engine preparation in the KLM test facility.

Some physics

The main reason to test an engine in a test cell is basically to prove that the engine is capable of providing the minimum required certified engine thrust.

Jet engines develop thrust in accordance with Sir Isaac Newton’s famous third law: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.

This principle and the forces in flight are depicted in the figure below:

It is a force, which we call thrust, that we are interested in. When testing the engine, we want to be absolutely sure that the engine still develops the amount of thrust that it should, even after it has been completely disassembled and rebuilt.

What happens in a test cell?

In a test cell we simulate the situation of the engine on the aircraft wing. The engine is installed in a thrust frame, similar to the pylon construction of an aircraft where the engine is mounted.

This thrust frame is instrumented to record all the required data needed to monitor a test. It is mounted to the test facility in a locked position to prevent forward motion. During the test, the engine is operated over a range of engine speeds.

Apart from the developed thrust we are also interested in parameters such as:

fuel consumption;

oil consumption;

rotor speeds;

vibration levels

pressures and temperatures at various locations of the engine.

All this data is constantly tracked and recorded. Once the engine test is completed and all parameters meet the manufacturer’s specifications, the test is finalised. This usually takes up to a few hours.

To be able to store the engine for a longer period and to prevent corrosion in the fuel and oil system, these systems are filled with special fluids containing corrosion inhibitors.

Once finished, the test operator signs off the work, the engine undergoes its final inspection, and is readied for shipment to the aircraft.

A GE CF6 Engine in the KLM test facility

Some facts and figures

At KLM E&M we test about 200 engines each year.

An average engine test consumes about 5,000 litres of jet fuel.

An entire engine test including all the preparations can take up to 16 hours. The actual test run time takes a few hours depending on the required work.

The test facility at Schiphol Airport has been in operation since 1972 and we have conducted over 9,000 engine tests.

Inside the building with the engine running at full power, noise levels can increase to 140 decibels (threshold of pain). Outside the building, noise levels are within 60 decibels, well within the environmental requirements.

Watch this video to give you a better understanding of how jet engines are tested.

]]>https://blog.klm.com/how-do-we-test-jet-engines/feed/28Farewell to One of Our Last GE CF6-50 Engineshttps://blog.klm.com/farewell-to-one-of-our-last-ge-cf6-50-engines/
https://blog.klm.com/farewell-to-one-of-our-last-ge-cf6-50-engines/#commentsWed, 02 Dec 2015 09:00:30 +0000https://blog.klm.com/?p=24742The CF6-50 is heading for retirement. KLM still has a few of these engines, but their market value is very limited. After 43 years of service, we handed one of our last CF6-50 engines over to science. The engine was donated to the Delft University of Technology (TU Delft), where it was offloaded and stored […]

]]>The CF6-50 is heading for retirement. KLM still has a few of these engines, but their market value is very limited. After 43 years of service, we handed one of our last CF6-50 engines over to science.

The engine was donated to the Delft University of Technology (TU Delft), where it was offloaded and stored in the technical workshop used by the students of the Aerospace Engineering faculty.

This transfer didn’t just happen overnight. The entire process took several years to complete and involved numerous people and departments, from financial controlling to quality assurance and legal support.

Most engines are sold to other operators or to aircraft parts brokers. Their value varies from around EUR 100.000 euros to several million euros. The same applies if the engine is broken down into individual parts, with yield varying depending on age, technical status and market requirements.

Engine history

In December 1972, KLM took delivery of its first DC10-30 aircraft, the long-range version of the DC10, developed by McDonnell Douglas in the USA.

The wide-body era had just begun the previous year, with the introduction of the Boeing 747. This new generation jumbo jets required larger aircraft engines.

The DC10-30 was powered by three large turbofan engines, the CF6-50C, designed by General-Electric. The airline industry was expanding fast and many more versions of the successful CF6 engine were developed for various aircraft. Namely:

The CF6-50C for the A300;

The CF6-50E for the B747;

The CF6-80A for the A310 and B767;

The CF6-80C2 for various B747, B767 and MD11 models;

The CF6-80E1 for the Airbus A330;

The GE CF6 is one of the most successful engines in recent aviation history, with more than 6,000 rolling off the production line. Because they were highly reliability and fuel efficient, they are sold like hotcakes. KLM Engineering & Maintenance maintains most models of the CF6 engine, conducting more than 9,000 overhauls over the years.

The engine donated to Delft is a CF6-50C model used to power Airbus A300s operated by various airlines. It racked up 52.697 flight hours, completing 26.231 flights, and had been in KLM’s possession since 2004.

To give you some idea: 52.697 flight hours is equal to approximately 42 million kilometres. That means to the moon and back 55 times, or around the earth over 1,000 times!

Our ties with the academic world

KLM has long-standing ties with the Delft University of Technology (TU Delft), which has an outstanding Faculty of Aerospace Engineering. Many graduates of the TU Delft have gone on to successful careers at KLM or participated in cooperative programmes between KLM Engineering & Maintenance and TU Delft.

One of these cooperative programmes led to an analytical tool that assesses the performance of gas turbines. This tool was developed by KLM Engine Services, TU Delft and the Dutch National Aerospace Laboratory. Another example of cooperation is the AHEAD study.

Educational institutions like TU Delft are always seeking study and tuition materials, because students need to supplement their textbook knowledge with hands-on experience involving the real “hardware”.

The engine will not only be used for display, but also as a practical tool to teach students the fundamental design principles of gas turbines, as well as their aerodynamics and systems.

This is not the first aviation hardware that KLM has donated for educational purposes. A KLM Boeing 747 classic is now on display in a museum, and two Boeing 737 CFM56 engines were donated to a regional college (ROC) for aviation students.

Engineering masterpiece

We are confident that future generations of aeronautical engineers will benefit from the knowledge they gain from this masterpiece of engineering design, which played such an important role in aviation history. Without these huge engines, wide-body aircraft wouldn’t have been able to take off!

Rob Duivis is programme manager at KLM Engine Services and has worked with CF6 engines for over 40 years.